An estimated 5,000 people in the northern atolls are experiencing severe drought conditions with an additional 11,000 people affected by crop loss due to the lack of rain.

The Marshall Islands government has declared a state of emergency in the northern atolls.

Drinking water is being rationed and there is no water for bathing or other domestic purposes.

"Officials have found some families living on a gallon, or 3.8 litres, of water per day -- barely half of the international standard for emergency water requirements, and often the precursor to serious health conditions," said IOM spokesman Jumbe Omari Jumbe.

He says government aid ships have begun transporting US-donated supplies, including water containers and hygiene kits, from IOM warehouses.

"While this may not be a massive disaster in global terms, it is highly significant for this remote and fragile environment," Ashley Carl, the IOM's chief of mission for the Marshall Islands, said in a statement.

Australia is sending in desalination units to supplement those provided by the United States.